In order to meet the demand for higher integration of semiconductor devices, use of a three-dimensional integration technique to stack semiconductor devices in three dimensions has been proposed. Systems adopting this three-dimensional integration technique utilize a bonding system for bonding substrates such as, e.g., semiconductor wafers (hereinafter referred to as “wafers”) or the like.
Such a bonding system includes a surface modifying apparatus for modifying the surfaces of first and second substrates to be bonded, a hydrophilizing apparatus for hydrophilizing the modified first and second substrates, and a bonding apparatus for bonding the hydrophilized first and second substrates by a van der Waals force and hydrogen bonding (an intermolecular force). The bonding system further includes a substrate transfer device for transferring the first and second substrates between the respective apparatuses.
However, in the bonding system described above, the substrate transfer device transfers the first and second substrates to the bonding apparatus in a state in which the bonding surfaces of the first and second substrates serve as upper surfaces. Then, the bonding apparatus performs a bonding process after inverting the transferred first substrate and causing the bonding surface of the first substrate to serve as a lower surface so that the bonding surface faces the second substrate.
Therefore, in the bonding apparatus, a processing time is required to invert the substrate. In the bonding system described above, there is room for further improvement in terms of shortening the processing time of bonding the substrates in the bonding apparatus.